Top 10 Linux Shell Interview Questions and How to Solve Them

1. How to interrupt a shell script before it finishes?

Use the exit command. Supplying a non‑zero status, e.g. exit -1, forces the script to terminate with an error.

#!/bin/bash
 echo "Hello"
 exit -1
 echo "bye"

Running the script shows the exit -1 stops execution before the final echo runs.

2. How to remove the header (first line) of a file?

The sed command can delete the first line:

# sed '1 d' file.txt

Using the in‑place edit flag -i avoids redirection:

# sed -i '1 d' file.txt

3. How to check the length of a specific line in a text file?

Combine sed to print the desired line with wc -c to count bytes. For example, to get the length of line 5 in linuxmi.txt:

# sed -n '5 p' linuxmi.txt | wc -c

4. How to view all non‑printing characters in a file?

Open the file in vi and enable the list option:

vi file.txt
: set list

This displays characters such as ^M for carriage returns.

5. How to create a shared directory dir_xyz where group members can create or access files but only the creator can delete them?

Use the sticky bit together with group write/execute permissions:

# mkdir dir_xyz
# chmod g+wx dir_xyz
# chmod +t dir_xyz

The +t (sticky) bit ensures only the file owner, directory owner, or root can delete files.

6. What are the main stages of a Linux process lifecycle?

Waiting – the process is waiting for resources.

Running – the process is actively executing.

Stopped – the process has finished execution or received a stop signal.

Zombie – the process has terminated but remains in the process table.

7. How to use the cut command?

Extract the first 10 characters of a file:

# cut -c1-10 txt_linuxmi

Extract specific fields (e.g., columns 2, 5, and 7) using a delimiter:

# cut -d';' -f2 -f5 -f7 txt_linuxmi

8. What is the difference between cmp and diff ?

diff

shows the changes needed to make two files identical, while cmp compares files byte‑by‑byte and reports the first mismatch.

9. Can the echo command replace ls ?

Yes. echo * lists the contents of the current directory, producing the same output as ls in many cases.

10. What is an inode?

An inode is a data structure used by Linux/Unix file systems to store metadata about a file; each file has a unique inode number.